OFFSET
1,1
FORMULA
a(n) = Sum_{r=1..n} r*Product_{j=0..r-1} (q^n-q^j)^2/(q^r-q^j) with q=4.
PROG
(PARI) a(n) = {my(q=4); sum(r=1, n, r*prod(j=0, r-1, (q^n-q^j)^2/(q^r-q^j)))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Yuval Dekel (dekelyuval(AT)hotmail.com), Aug 27 2003
EXTENSIONS
a(6)-a(10) from Andrew Howroyd, Jul 08 2018
STATUS
approved